The present application refers to a sound-deadening device for a rotary saw blade which cuts by means of its periphery and which has a centre hole for the fastening of the blade to a suitable driving device. A saw blade in operation makes a disturbing sound, and for a long time it has been a problem how to bring down the sound level. Many attempts have been made with a certain degree of progress. The body of the saw blade is usually homogeneous and, according to the Swiss Pat. No. 183,743, cuttings have been made in homogeneous saw blades and in accordance with the patent the cuttings have been filled with a lead alloy or an aluminium alloy. According to the patent, melted lead has been poured down into the cuttings and then the surface of the saw blade has been made plane and smooth. This must be a troublesome and complicated operation as saw blades, in accordance with the patent, have not emerged on the market in spite of the fact that the requirement for a sound deadening is very great today, and in spite of the fact that there is very heavy pressure from environmental authorities. Another way of reducing the sound level has been to employ two saw blades, which have been put on each other, and then welded together, or glued to each other. From an economic point of view, this has not been a favourable method because when such a blade has become crooked it is very difficult to straighten, and therefore the blade will, in most cases, be discarded.